[absherwin]

If we assume the main problem with lotteries is that they make some people poorer, we need to solve two things: The payout being less than the cost due to both high overhead and transfers and the payouts tending to concentrate wealth since even in a lifetime of play few win the largest jackpots.

One can't make them too flat because consumers like large jackpots which is why they've grown over time and become harder to win. Presumably there's a level below which consumers would switch to other types of gambling regardless of legality.